Field of Technology
The present disclosure relates to an organic light emitting display (OLED) device and more particularly to a flexible OLED device that prevents damage of an organic emitting diode and a display quality degradation problem.
Discussion of the Related Art
As information technology and mobile communication technology have been developed, a display device capable of displaying a visual image has also been developed. Flat panel display devices, such as a liquid crystal display (LCD) device and an OLED device, are developed and used.
Among these flat panel display devices, since the OLED device has advantages in response time, contrast ratio, viewing angle, power consumption, and so on, the OLED device is widely developed.
An emitting diode including an organic emitting layer is susceptible to damage from moisture. To prevent moisture penetration into the emitting diode and to protect the emitting diode from external impacts, an encapsulation substrate of glass is attached onto the emitting diode.
Recently, flexible, rollable, or bendable display devices (hereinafter “flexible display device”) have been introduced.
In the flexible OLED device, an encapsulation film including an inorganic layer and an organic layer is used instead of the encapsulation substrate. Namely, by using the encapsulation film for preventing moisture penetration into the emitting diode and to protect the emitting diode, the display device has a flexible property.
FIG. 1 is a schematic cross-sectional view of the related art OLED device.
As shown in FIG. 1, the OLED device 1 includes a flexible substrate 10, where a display area AA and a non-display area NA at a periphery of the display area AA are defined, an organic emitting diode D on or over the flexible substrate 10 and an encapsulation film 20 covering the organic emitting diode D.
The flexible substrate 10 may include polymer such as polyimide, and the organic emitting diode D is formed on or over the flexible substrate 10. The organic emitting diode D is positioned in the display area AA, and a driving part (not shown) for driving the organic emitting diode D is positioned in the non-display area NA.
Although not shown, the organic emitting diode D may include first and second electrodes facing each other and an organic emitting layer between the first and second electrodes. In addition, on the flexible substrate 10, a switching thin film transistor (TFT) as a switching element and a driving TFT as a driving element are formed, and the first electrode of the emitting diode D is connected to the driving TFT.
The encapsulating film 20 covers the organic emitting diode D and corresponds to the display area AA and the non-display area NA. The encapsulating film 20 prevents damage to the emitting diode D under conditions of high temperature and high humidity.
In the encapsulation film 20, an inorganic layer and an organic layer are alternately stacked. For example, the encapsulation film 20 may have a triple-layered structure including a first inorganic layer 22 on the emitting diode D, an organic layer 24 on the first inorganic layer 22, and a second inorganic layer 26 on the organic layer 24.
A barrier film 30 is attached to the encapsulation film 20 using an adhesive layer 32.
However, when the flexible OLED device 1 is operated under a condition of high temperature and high humidity, the emitting diode D is still damaged resulting in problems in display quality and a lifetime of the flexible OLED device 1.